package org.bouncycastle.asn1;

import java.io.IOException;
import java.io.OutputStream;

public class BEROctetStringGenerator extends BERGenerator {
    public BEROctetStringGenerator(OutputStream out) throws IOException {
        super(out);

        writeBERHeader(DERTags.CONSTRUCTED | DERTags.OCTET_STRING);
    }

    public BEROctetStringGenerator(OutputStream out, int tagNo, boolean isExplicit) throws IOException {
        super(out, tagNo, isExplicit);

        writeBERHeader(DERTags.CONSTRUCTED | DERTags.OCTET_STRING);
    }

    public OutputStream getOctetOutputStream() {
        return getOctetOutputStream(new byte[1000]); // limit for CER encoding.
    }

    public OutputStream getOctetOutputStream(byte[] buf) {
        return new BufferedBEROctetStream(buf);
    }

    private class BufferedBEROctetStream extends OutputStream {
        private byte[] _buf;
        private int _off;

        BufferedBEROctetStream(byte[] buf) {
            _buf = buf;
            _off = 0;
        }

        public void write(int b) throws IOException {
            _buf[_off++] = (byte) b;

            if (_off == _buf.length) {
                _out.write(new DEROctetString(_buf).getEncoded());
                _off = 0;
            }
        }

        public void write(byte[] b, int off, int len) throws IOException {
            while (len > 0) {
                int numToCopy = Math.min(len, _buf.length - _off);
                System.arraycopy(b, off, _buf, _off, numToCopy);

                _off += numToCopy;
                if (_off < _buf.length) {
                    break;
                }

                _out.write(new DEROctetString(_buf).getEncoded());
                _off = 0;

                off += numToCopy;
                len -= numToCopy;
            }
        }

        public void close() throws IOException {
            if (_off != 0) {
                byte[] bytes = new byte[_off];
                System.arraycopy(_buf, 0, bytes, 0, _off);

                _out.write(new DEROctetString(bytes).getEncoded());
            }

            writeBEREnd();
        }
    }
}
